5-quantum-teleportation.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Quantum teleportation"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "trusted": true
   },
   "outputs": [],
   "source": [
    "import os\n",
    "import qiskit"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We need to create an empty circuit with 3 qubits and 3 classical bits."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "trusted": true
   },
   "outputs": [],
   "source": [
    "# Prepares 3 qubit (initialized to 0 by default)\n",
    "q = qiskit.QuantumRegister(3, \"q\")\n",
    "\n",
    "# Prepares 3 classical bit (initialized to 0 by default)\n",
    "c0 = qiskit.ClassicalRegister(1, \"c0\")\n",
    "c1 = qiskit.ClassicalRegister(1, \"c1\")\n",
    "c2 = qiskit.ClassicalRegister(1, \"c2\")\n",
    "\n",
    "# Creates a quantum circuit\n",
    "circuit = qiskit.QuantumCircuit(q, c0, c1, c2)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Prepare the initial state of the qubit to be teleported."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "trusted": true
   },
   "outputs": [],
   "source": [
    "circuit.x(q[0])\n",
    "\n",
    "# Barrier to prevent gate reordering for automatic optimization\n",
    "circuit.barrier(q)\n",
    "\n",
    "circuit.draw()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Measure qubits 0 and 1."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "trusted": true
   },
   "outputs": [],
   "source": [
    "circuit.cx(q[0], q[1])\n",
    "circuit.h(q[0])\n",
    "\n",
    "circuit.barrier(q)\n",
    "\n",
    "circuit.measure(q[0], c0[0])\n",
    "circuit.measure(q[1], c1[0])\n",
    "\n",
    "circuit.barrier(q)\n",
    "circuit.draw()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "If needed, perform a phase correction to qubit 2 before the measurement."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "trusted": true
   },
   "outputs": [],
   "source": [
    "circuit.z(q[2]).c_if(c0, 1)\n",
    "circuit.x(q[2]).c_if(c1, 1)\n",
    "\n",
    "circuit.measure(q[2], c2[0])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Prepare a quantum simulator."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "trusted": true
   },
   "outputs": [],
   "source": [
    "simulator = qiskit.Aer.get_backend('qasm_simulator')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Run the circuit using a simulator."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "trusted": true
   },
   "outputs": [],
   "source": [
    "# Executes the quantum circuit on the simulator for 1,000 times\n",
    "job = qiskit.execute(circuit, simulator, shots=1000)\n",
    "print(job.result().get_counts())"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Prepare a real quantum computer."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "trusted": true
   },
   "outputs": [],
   "source": [
    "# Gets your IBM-Q user account\n",
    "if os.environ[\"IBMQ_TOKEN\"]:\n",
    "    qiskit.IBMQ.save_account(os.environ[\"IBMQ_TOKEN\"])\n",
    "provider = qiskit.IBMQ.load_account()\n",
    "\n",
    "# Gets all available backends (excluding simulators)\n",
    "backends = provider.backends(simulator=False)\n",
    "\n",
    "# Uses the least busy quantum backend\n",
    "backend = qiskit.providers.ibmq.least_busy(backends)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": "Run the circuit using a quantum computer."
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "trusted": true
   },
   "outputs": [],
   "source": "print(\"Running on:\", backend.name())\n\n# Executes the quantum circuit on a quantum backend for 1,000 times\njob = qiskit.execute(circuit, backend, shots=1000)\nprint(job.result().get_counts())"
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.7.3"
  },
  "pycharm": {
   "stem_cell": {
    "cell_type": "raw",
    "source": [],
    "metadata": {
     "collapsed": false
    }
   }
  }
 },
 "nbformat": 4,
 "nbformat_minor": 2
}